1. Technical Field
The present invention relates to a method for bonding two or more optical parts and an optical apparatus using the method.
2. Description of the Prior Art
In designing, processing or manufacturing fiber optical components, it is often necessary to bond two or more optical parts together. Traditionally, in the process of bonding two optical parts with flat surfaces, some kinds of bonding adhesives such as epoxies and acrylics are often used. However, most of the adhesives that have acceptable performances for the fiber optical device applications either have a very low viscosity to begin with, or their viscosity becomes lower in the curing process (e.g. UV curing or thermal curing). As a result, some adhesive substances can go into the interface gap between the two flat surfaces of the optical parts being bonded due to the well-known capillary effect if there are no isolation frames, or spacers in between the two flat surfaces. To eliminate the capillary effect, a frame (e.g. metal or plastic material) is often used to maintain a minimum distance between the two flat surfaces, as shown in FIG. 1A. FIG. 1B shows that two optical parts are bonded together with a frame in between as a spacer. But this traditional solution has some drawbacks. First of all, since most of fiber optical devices are very small, most likely, the frame must be machined with very high precision, therefore, it can be costly. In addition, since the frame must be somehow fixed to a substrate to complete the whole component, it will add difficulty and complexity to the overall mechanical characteristics, which in turn will reduce the stability and reliability of this device, especially over long time and in a harsh temperature and mechanical environment.
There is thus a great need for an economic and reliable solution to bonding two or more optical parts together.
The present invention, generally speaking, provides an economic and reliable solution to bonding two or more parts with, preferably, flat surfaces by using optical fibers as a spacer. Since optical fibers are readily available in many situations, the present invention offers many unanticipated advantages and/or benefits. First of all, the present invention eliminates the need to customize particular spacers when two parts to be bonded show some irregularities, optical fibers can be cut in any length to accommodate the special situation. Secondly, the separation space created by the optical fiber (the diameter of a common single mode fiber without buffer is 0.125 mm) is just right to eliminate the capillary effect for most commonly used adhesives. Another advantage and benefit of the present invention is that the fiber spacer solution is much economic compared to the frame based solutions.
Other objects, features, and advantages of the present invention will become apparent upon examining the following detailed description of an embodiment thereof, taken in conjunction with the attached drawings.